Some devices and/or systems collect data in remote and/or physically inaccessible environments and transmit the data to receiving stations in accessible environments. For example, scientists in receiving stations retrieve data from unmanned underwater vehicles (also referred to here as a “vehicle”) located miles under the ocean or from space vehicles orbiting above the atmosphere of the earth (also referred to here as a “vehicle” or an “airborne vehicle”). If a portion of the devices or systems (also collectively referred to here as “units under test” and individually as a “unit under test”) fails while in the inaccessible environment, it is not possible for an operator to locally test with a probe, examine and/or replace any failed unit under test or any portion thereof.
In some cases, the inaccessible devices and/or systems include redundant systems, where a secondary or “backup” device or system is activated in order to replace a failed “primary” device or system. Additionally in some cases, software (or other programmable devices) in the inaccessible devices and/or systems is re-programmable. In that case, the software is reprogrammed to avoid using the defective devices and/or systems while the overall system remains operational. In either of these cases, an operator in the receiving station must know which component and/or components have failed in order to take the corrective action. In this situation, it is necessary to diagnose the problem remotely since it is not possible to locally probe, examine and/or replace any failed parts of the unit under test.